The Shulchan Aruch 225:1 brings the halachah what when one sees a "friend" whom one hasn't seen in the last 30 days then the blessing "shehecheyanu" is made, and if one has not seen them in twelve months then the blessing "m'chayeh hameisim" is made.

Double AA has championed the position of Rav Ovadia Yosef shlita who takes issue with the Mishneh Berurah for not distinguishing between the case where one says shehecheyanu and the case where one says m'chayeh hameisim regarding a friend you have received a letter from or otherwise heard of his well being. Indeed, when we follow the chain back we do see that many/most/all of the sources which discuss do so in the context of the berachah m'chayeh hameisim. It seems to me that we are left with two opposing challenges:

On what basis do we learn the MB as applying this halachah to both cases? While my limited survey it seems that most secondary sources and apparently other Poskim learn the Misheh Berurah that way, is this really necessary. The Mishneh Berurah 225:2 writes, "ואם קבל ממנו כתב או שאנשים הודיעהו משלומו, יש דעות באחרונים, וספק ברכות להקל" with no specific mention of the berachah shecheyanu. If we infer it from the location the se'if katan commented on (הרואה את חברו), at the head of the halachah where both berachos are located, then the same is true of the Sha'arei Teshuvah which writes, "ומ"ש בשם הלק"ט בקבל ממנו כתב כו', וע"ש דמשמע שאף אם באו אנשים שהודיעו משלומו, וכן בבר"י בשם מז"ה משמע דגם אם הוא יודע משלומו אף שלא כתב לו אין מברך,וצ"ע" which is commenting on the same location and neither mentions both blessings explicitly nor limits the ruling to one blessing. Do we have reason to learn this Mishneh Berurah as applying to both berachos, and if so on what basis do we not learn the Sha'arei Teshuvah in the same manner to deny the Mishneh Berurah precedent (even if it only pushes the question back onto Sha'arei Teshuvah).

Conversely, on what basis do we make a distinction between the two blessings throughout the Gemara and Poskim the halachos pertaining to the חבר are given jointly, with the only explicit distinction being whether the friend has been gone 30 days or 12 months. Given that all other halachos regarding who this berachah is said upon seeing are identical, what precedent do we have for making a distinction. If we learn Mishneh Berurah and/or Sha'arei Teshuvah as treating these berachos as equivalent, what is to prevent them from learning the earlier poskim who mention the issues of receiving letters with respect the the berachah m'chayeh hameisim as being "lav davka" (such as the aforementioned Birchei Yosef, perhaps others may not be as open to such an interpretation)? During those generations I suspect (just a hypothesis) that sending a letter to someone who had been gone less than an month wasn't exactly practical and presumably uncommon. Where, other than Rav Ovadiah Yosef, do we see explicit basis to differentiate the situations where these blessings are said beyond the defining difference of the length of absence?

It seems the reason to split is based on the text of the blessing which implies different forms of emotion (joy over seeing vs joy over living).

EDIT: Also, it seems the Halchot Ketanot 1:220 (quoted Be'er Heitev 225:1 and in the Sha'arei Teshuva you quote) explicitly differentiates between the two and says "possibly to not say Mechaye HaMetein but certainly to say Shehchiyanu." Note that this work dates from 1704.

yasher koach, I couldn't figure out the roshei teivos for Halchot Ketanot for the live of me :) Now I'll look at it.
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YirmeyahuFeb 21 '12 at 5:13

@Yirmeyahu Note how the H"K is seemingly unsure but siding lechumra in terms of Michaye Meitim, as if that was a chiddush and it was peshita leih the other way for shehechiyanu.
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Double AA♦Feb 21 '12 at 5:15